Acute
headache medication overuse (MO) is common in patients with chronic
migraine (CM). We evaluated safety and efficacy of
onabotulinumtoxinA as preventive treatment of
headache in CM patients with baseline MO (CM+MO) in a planned secondary analysis from two similarly designed, randomized, placebo-controlled, parallel, Phase III trials. Patients were randomized to treatment groups (155-195 U of
onabotulinumtoxinA or placebo) using MO (patient-reported and diary-captured frequency of intake) as a stratifying variable. Of 1384 patients, 65.3% (n=904) met MO criteria (
onabotulinumtoxinA: n=445, placebo: n=459). For the CM+MO subgroup at Week 24, statistically significant between-treatment group mean changes from baseline favoring
onabotulinumtoxinA versus placebo were observed for
headache days (primary endpoint: -8.2 vs. -6.2; p<0.001) and other secondary endpoints: frequencies of
migraine days (p<0.001), moderate/severe
headache days (p<0.001), cumulative
headache hours on
headache days (p<0.001),
headache episodes (p=0.028), and
migraine episodes (p=0.018) and the percentage of patients with severe
Headache Impact Test-6 category (p<0.001). At Week 24, change from baseline in frequency of acute
headache medication intakes (secondary endpoint) was not statistically significant (p=0.210) between groups, except for
triptan intakes (p<0.001), where the
onabotulinumtoxinA-treated group was favored.
OnabotulinumtoxinA was effective and well tolerated as
headache prophylaxis in CM+MO patients.